1. Field of the Invention
This invention relates to a pneumatic tire having a tread pattern of an outer surface of a tread defined by grooves.
2. Description of the Related Art
As a tread pattern of the pneumatic tire, there have hitherto been known a so-called rib type pattern in which plural main grooves extending zigzag in the circumferential direction are formed on the outer surface of the tread portion to form plural ribs located between adjoining main grooves and between the main groove and the tread end, or a so-called block type pattern in which plural main grooves extending in the circumferential direction and plural transverse grooves extending substantially extending in the axial direction and crossing with the main grooves are formed on the outer surface of the tread portion to form many polygonal blocks.
in the conventional pneumatic tire, however, maximum cornering force largely lowers at a large steering angle to degrade running performances of the tire on dry road.